Heredoc and nowdoc syntax in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a heredoc string with the identifier TEXT.

PHP

<?php
$heredoc = <<<[1]
This is a heredoc string.
TEXT;
?>

Drag options to blanks, or click blank then click option'

Atext

B'TEXT'

CTEXT

D"TEXT"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the identifier in heredoc start.

Using lowercase letters that don't match the closing label.

Heredoc syntax starts with <<<IDENTIFIER where IDENTIFIER is an unquoted label like TEXT.

2fill in blank

medium

Complete the code to start a nowdoc string with the identifier DATA.

PHP

<?php
$nowdoc = <<<'[1]'
This is a nowdoc string.
DATA;
?>

Drag options to blanks, or click blank then click option'

ADATA

Bdata

C"DATA"

D'DATA'

Attempts:

3 left

💡 Hint

Common Mistakes

Using double quotes instead of single quotes for nowdoc.

Not matching the closing label with the starting identifier.

Nowdoc syntax uses single quotes around the identifier after <<<, like <<<'DATA'.

3fill in blank

hard

Fix the error in the heredoc closing label to properly end the string.

PHP

<?php
$text = <<<EOT
Hello, world!
[1];
?>

Drag options to blanks, or click blank then click option'

AEOT

B'EOT'

C"EOT"

DEot

Attempts:

3 left

💡 Hint

Common Mistakes

Indenting the closing label.

Using quotes around the closing label.

Changing the case of the closing label.

The closing label must exactly match the starting identifier and be at the start of the line with no indentation.

4fill in blank

hard

Fill both blanks to create a heredoc string that includes a variable $name.

PHP

<?php
$name = "Alice";
$message = <<<[1]
Hello, [2]!
[1];
?>

Drag options to blanks, or click blank then click option'

AGREETING

B$name

Cname

D'name'

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the heredoc identifier.

Not using the $ sign before the variable inside heredoc.

The heredoc identifier can be any label like GREETING. Variables inside heredoc are parsed, so use $name.

5fill in blank

hard

Fill all three blanks to create a nowdoc string that includes the literal text $name without parsing.

PHP

<?php
$name = "Bob";
$text = <<<'[1]'
Hello, [2]!
[3];
?>

Drag options to blanks, or click blank then click option'

ADATA

B$name

Attempts:

3 left

💡 Hint

Common Mistakes

Using double quotes around the nowdoc identifier.

Trying to parse variables inside nowdoc.

Nowdoc uses single quotes around the identifier DATA. Inside nowdoc, variables like $name are not parsed and appear as literal text. The closing label must match the identifier exactly.

Practice

1. What is the main difference between heredoc and nowdoc syntax in PHP?

easy

A. Nowdoc parses variables inside the string, heredoc does not.

B. Neither heredoc nor nowdoc parse variables inside the string.

C. Both parse variables inside the string the same way.

D. Heredoc parses variables inside the string, nowdoc does not.

Solution

1. Step 1: Understand heredoc behavior

   Heredoc syntax allows variables inside the string to be replaced with their values.

2. Step 2: Understand nowdoc behavior

   Nowdoc syntax treats the string as plain text, so variables are not replaced.

3. Final Answer:

   Heredoc parses variables inside the string, nowdoc does not. -> Option D

4. Quick Check:

   Heredoc = variable parsing, Nowdoc = no parsing [OK]

Hint: Remember: heredoc = variables parsed, nowdoc = raw text [OK]

Common Mistakes:

• Thinking nowdoc parses variables like heredoc
• Confusing which syntax uses single quotes
• Assuming both behave the same with variables

2. Which of the following is the correct syntax to start a nowdoc string in PHP?

easy

A. <<<'EOD'

B. <<

C. <<<"EOD"

D. <<

Solution

1. Step 1: Identify nowdoc syntax start

   Nowdoc starts with <<< followed by a single-quoted identifier, like <<<'EOD'.

2. Step 2: Compare options

   <<<'EOD' uses single quotes correctly; others use no quotes or double quotes which are for heredoc or invalid.

3. Final Answer:

   <<<'EOD' -> Option A

4. Quick Check:

   Nowdoc uses single quotes around identifier [OK]

Hint: Nowdoc always uses single quotes around the identifier [OK]

Common Mistakes:

• Using double quotes or no quotes for nowdoc start
• Adding semicolon after the identifier
• Confusing heredoc and nowdoc start syntax

3. What will be the output of the following PHP code?

$name = "Alice";
$text = <<

medium

A. Hello, $name!

B. Hello, Alice!

C. Syntax error

D. Hello, ;

Solution

1. Step 1: Understand heredoc variable parsing

   The heredoc syntax replaces variables like $name with their values inside the string.

2. Step 2: Apply variable value

   $name is "Alice", so the output becomes "Hello, Alice!".

3. Final Answer:

   Hello, Alice! -> Option B

4. Quick Check:

   Heredoc parses variables = Hello, Alice! [OK]

Hint: Heredoc replaces variables with their values automatically [OK]

Common Mistakes:

• Thinking heredoc outputs variable names literally
• Confusing heredoc with nowdoc behavior
• Expecting syntax error due to variable inside heredoc

4. Identify the error in this PHP code snippet using nowdoc:

$text = <<<'EOD'\
This is a nowdoc string.
EOD;
echo $text;

medium

A. Missing semicolon after nowdoc start identifier

B. Incorrect closing identifier syntax

C. Extra backslash after nowdoc start identifier

D. Syntax error due to single quotes around identifier

Solution

1. Step 1: Check nowdoc start syntax

   Nowdoc start must be followed immediately by a newline, no extra characters like backslash after the identifier.

2. Step 2: Identify error in code

   The code has a backslash after <<<'EOD' which is invalid syntax; it should be just <<<'EOD' followed by newline.

3. Final Answer:

   Extra backslash after nowdoc start identifier -> Option C

4. Quick Check:

   Nowdoc start line ends immediately after identifier, no extra chars [OK]

Hint: Nowdoc start line ends immediately after identifier, no extra chars [OK]

Common Mistakes:

• Adding backslash or semicolon after nowdoc start
• Using double quotes instead of single quotes
• Misplacing closing identifier

5. You want to store a multi-line SQL query in a PHP variable without parsing variables inside it. Which syntax should you use and why?

$query = ???
SELECT * FROM users WHERE name = '$name';
???;

hard

A. Use nowdoc to keep the query text exactly as typed, no variable parsing.

B. Use single quotes with concatenation for variables.

C. Use double quotes with escaped variables inside the string.

D. Use heredoc to allow variable parsing for dynamic queries.

Solution

1. Step 1: Understand requirement

   The query should keep variables like $name as plain text, not replaced by PHP values.

2. Step 2: Choose correct syntax

   Nowdoc syntax keeps the string exactly as typed, so variables are not parsed, perfect for raw SQL queries.

3. Final Answer:

   Use nowdoc to keep the query text exactly as typed, no variable parsing. -> Option A

4. Quick Check:

   Nowdoc = raw text, no variable parsing [OK]

Hint: Use nowdoc for raw multi-line strings without variable parsing [OK]

Common Mistakes:

• Using heredoc and expecting variables not to parse
• Trying to escape variables inside double quotes unnecessarily
• Concatenating strings instead of using nowdoc for raw text